The primary objective of a cleaning composition is to remove soil from an article. In the case where the cleaning composition is a laundry detergent and the article to be cleaned is not highly stained, surfactants, builders and enzymes formulated into most detergents are adequate to completely remove soil from the article. When stronger cleaning power is needed to remove soil from the article other products such as bleach or laundry boosters are used in addition to the detergent. In addition, washing with hotter water, using longer wash cycles, pre-soaking the soiled article in an aqueous solution containing detergent, or using a spot pretreater are helpful for removing soil.
However, where the article is heavily soiled, or where the soil has penetrated into the article, surfactants, builders, enzymes, bleach, or laundry boosters are not always completely effective in removing soil from an article. Spot pretreaters are useful, but they need to be applied to the stained area prior to washing requiring an inconvenient additional step in the washing process. Additionally, certain soils are particularly difficult to remove from certain types of articles. For example, oil based soils are particularly difficult to remove from synthetic fabrics, and ground in clay or particulate stains are particularly difficult to remove from cotton fabrics. In addition, removing soil can be made more difficult when soil which is suspended in the washing process redeposits onto the article.
Soils commonly found on stained articles include oil and oily particulate stains such as frying oils or grease, sauces like tomato or spaghetti sauce, tea or coffee stains; non-saponifiable oil stains such as used motor oil or petroleum oils; grass stains; enzyme sensitive stains such as fats or proteins; and mineral stains such as clays.
Several solutions have been proposed for improving the cleaning of an article. One proposed solution for cleaning of an article is to add a "soil removal agent" to a cleaning composition to increase soil removal from the article during cleaning. Another proposed solution involves protecting an article with a "soil resistant agent" so that soil is not deposited as easily on the article in comparison to another article not protected by the soil resistant agent. The soil resistant agent may also act to protect the article by making soil on an article easier to remove in comparison to another article which was not protected by the soil resistance agent before being soiled. Another proposed solution involves adding an agent which inhibits soil which has been removed from an article during cleaning from depositing onto the same or different article.
U.S. Pat. No. 3,485,762 describes using styrene-maleic anhydride copolymers derivatized with polyethylene glycols in detergent compositions. While the detergent compositions are effective for removing soil from hydrophobic articles such as polyester, such copolymers are not as effective on hydrophilic articles such as cotton.
U.S. Pat. No. 4,444,561 describes using copolymers prepared from 50 to 90 weight percent of a vinyl ester of C.sub.1 -C.sub.4 aliphatic carboxylic acids, from 5 to 35 weight percent of a N-vinyl lactam, and from 1 to 20 weight percent of a monomer containing basic nitrogen capable of forming a salt or quaternized product, in detergent compositions to inhibit soil redeposition. The disadvantage of using such copolymers, however, is that they are capable of forming cations which may complex with anionic surfactants under certain wash conditions and cause a decrease in cleaning performance. In addition, the cationic copolymers may also undesirably promote fabric greying over multiple washing cycles.
U.S. Pat. No. 5,008,032 describes using copolymers prepared from C.sub.4 -C.sub.26 olefins and .alpha.,.beta.-ethylenically unsaturated dicarboxylic anhydrides in detergent formulations. The disadvantage of using such copolymers, however, is that the copolymers are not water -soluble unless hydrolyzed with NaOH.
U.S. Pat. No. 5,580,941 describes using a water-soluble, acid-group containing graft copolymer in detergent formulations. The graft copolymer is obtained by copolymerizing a monomer mixture in the presence of a sugar. The monomer mixture contains a monoethylenically unsaturated C.sub.3 to C.sub.10 monocarboxylic acid, or salt thereof with a monovalent cation, and a monoethylenically unsaturated monomer comprising a monosulfonic acid group, monoethylenically unsaturated sulfuric acid ester, vinylphosphonic acid or salt thereof with a monovalent cation. The disadvantage of using such copolymers, however, is that they are capable of forming cations which may complex with anionic surfactants under certain wash conditions and cause a decrease in cleaning performance. In addition, the cationic copolymers may also undesirably promote fabric greying over multiple washing cycles.
European Patent Application 753 570 A2 describes a soil removal and soil resistant detergent composition containing a vinyl amide polymer which is prepared from 5 to 100 weight percent of a vinyl amide monomer and from 0 to 95 weight percent of a vinyl ester monomer. While the detergent compositions are effective for removing soil from hydrophobic articles such as polyester, such compositions are not as effective for cleaning hydrophilic substrates such as cotton.